An endpoint such as a mobile node may use a system of communication networks to communicate packet flows with other endpoints. For example, a mobile node may be associated to a home network that maintains subscription information for the mobile node. If the mobile node is outside of the range of the home network, the mobile node may use a visited network to communicate packet flows.
Certain known techniques may be used to route packet flows between endpoints and through networks. These known techniques, however, are not efficient in certain situations. In certain situations, it is generally desirable to be efficient. Accordingly, signaling mechanisms have been establish that allow visited and home networks to optimally establish split policy enforcement with media flows being egressed by the visited network anchor and other flows, e.g., signaling or client-server flows, or off-net traffic to be egressed by the home network.
Several major trends are coming together to drive the adoption of packet-based radio technologies and Internet Protocol (IP)-based network architectures. There is a simultaneous desire to remove elements which process user plane data in wireless systems. Some of these new proposed architectures have a direct connection between the access point or node providing wireless protocol termination and the element providing policy enforcement. The system architecture facilitates both optimized routing of media streams and may limit the aggregated cell/transitions per second. For example, in some proposed mobile carrier architectures, a base station may provide the access layer to one or more mobile nodes, while an IP gateway may provide the distribution layer. In some proposed architectures, the base stations may be operable to directly communicate with the IP gateway or indirectly via a mesh net work of base stations. Since the upper tier policy enforcement node (such as an IP gateway) will be a mobility anchor, it will be signaled on cell transitions.
This flat hierarchy between the access point and the policy enforcement point (e.g., where the distribution and policy enforcement layers are closer to the network edge) and the possible use of optimized routing for media streams present certain challenges when considering mobility. Given the non-split nature of the IP gateway, an access point (e.g., enhanced node B) can normally be in communication with multiple IP gateways. This can allow, for instance, minimized delay in the relocation of an IP gateway for a roaming mobile node until active media streams have terminated. For example, an IP gateway may be relocated when a handset is in idle mode, since the IP gateway has no current media streams associated with the roaming mobile node to process. There may be situations, however, when the relocation of the IP gateway cannot be delayed. Examples include when a mobile node roams to a cell connected to an IP gateway that is managed by a different administrative domain (e.g., in the network of a different public land mobile network (PLMN)). In another example, transmission network restrictions may prevent the new access point from remaining in contact with the previous IP gateway.